<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        #d2 {
            width: 100px;
            height: 100px;
            border: 1px solid red;
            /*内边距会影响元素的显示尺寸*/
            padding-left: 50px;
            padding-top: 50px;
            /*添加此样式后,给元素添加边框和内边距时不会影响元素的宽高*/
            box-sizing: border-box;

        }
    </style>
</head>
<body>
<div id="d2">内边距</div>
</body>
</html>